Data from: Artificial light at night decreases metamorphic duration and juvenile growth in a widespread amphibian

Artificial Light at Night (ALAN) affects over 20% of the earth’s surface and is estimated to increase 6% per year. Most studies of ALAN have focused on a single mechanism or life-stage. We tested for indirect and direct ALAN effects that occurred by altering American toads’ (Anaxyrus americanus) ecological interactions or by altering toad development and growth, respectively. We conducted an experiment over two life-stages using outdoor mesocosms and indoor terraria. In the first phase, the presence of ALAN reduced metamorphic duration and periphyton biomass. The effects of ALAN appeared to be mediated through direct effects on toad development, and we found no evidence for indirect effects of ALAN acting through altered ecological interactions or colonization. In the second phase, post-metamorphic toad growth was reduced by 15% in the ALAN treatment. Juvenile-stage ALAN also affected toad activity: in natural light, toads retreated into leaf litter at night whereas ALAN toads did not change behaviour. Carry-over effects of ALAN were also present; juvenile toads that had been exposed to larval ALAN exhibited marginally increased activity. In this time frame and system, our experiments suggested ALAN’s effects act primarily through direct effects, rather than indirect effects, and can persist across life-stages.夜间人工光（Artificial Light at Night, ALAN）已影响地球超20%的地表面积，且据估算其覆盖范围正以每年6%的速率扩张。现有针对夜间人工光的研究大多仅聚焦于单一作用机制或单一生命阶段。本研究针对夜间人工光的间接与直接作用效应展开测试：前者通过改变美洲蟾蜍（Anaxyrus americanus）的生态相互作用实现，后者则直接作用于蟾蜍的发育与生长过程。本研究采用室外中宇宙实验系统与室内饲养箱，针对蟾蜍的两个生命阶段开展了对照实验。实验第一阶段中，夜间人工光的存在缩短了蟾蜍的变态时长，并降低了周丛生物的生物量。研究结果显示，夜间人工光的效应似乎通过直接作用于蟾蜍发育过程实现，未发现其通过改变生态相互作用或物种定植过程产生间接效应的证据。实验第二阶段中，经夜间人工光处理的蟾蜍，其变态后的生长速率较对照组降低了15%。幼体阶段暴露于夜间人工光环境下同样会影响蟾蜍的行为活动：在自然光环境中，蟾蜍会在夜间退缩至落叶凋落物下休憩，而经夜间人工光处理的蟾蜍则未表现出此类行为变化。夜间人工光还存在跨生命阶段遗留效应：曾于幼体阶段暴露于夜间人工光环境的幼蟾，其活动水平呈现小幅提升。基于本实验的时间尺度与实验系统，研究结果表明夜间人工光的生态效应主要通过直接作用途径产生，而非间接作用，且该效应可跨生命阶段持续存在。